SUM的SQL MAX没有子查询

Question

我正在尝试执行一个SQL查询，该查询需要按照MAX的SUM计算进行分组（在PostgreSQL中）。

我在这里找到了一些使用子查询的解决方案，但我需要没有它的解决方案（如果可能的话）。

查询：

SELECT "Festival".title,
       "Musician".aname, 
       SUM("Musician".salary * "Musician".percentage / 100) AS "agent_total_profit"
FROM "Festival"
INNER JOIN "Booked" 
    ON "Booked".title = "Festival".title
INNER JOIN "Musician"
    ON "Musician".id = "Booked".id
GROUP BY "Festival".title, 
         "Musician".aname
ORDER BY "Festival".title

结果：

结果不符合预期，我想找到每个节日标题，音乐家和最大的agent_total_profit。

期望的结果：

提前致谢。

Answer 1

使用DISTINCT ON：

SELECT DISTINCT ON (f.title) f.title, m.aname, 
       SUM(m.salary * m.percentage / 100) AS "agent_total_profit"
FROM "Festival" f INNER JOIN
     "Booked" b
     ON b.title = f.title INNER JOIN
     "Musician" m
    ON m.id = b.id
GROUP BY f.title, m.aname
ORDER BY f.title, "agent_total_profit" DESC;

更传统的SQL方法使用row_number()：

SELECT f.*
FROM (SELECT f.title, m.aname, 
             SUM(m.salary * m.percentage / 100) AS "agent_total_profit",
             ROW_NUMBER() OVER (PARTITION BY f.title ORDER BY SUM(m.salary * m.percentage / 100) DESC) as seqnum
      FROM "Festival" f INNER JOIN
           "Booked" b
           ON b.title = f.title INNER JOIN
           "Musician" m
          ON m.id = b.id
      GROUP BY f.title, m.aname
     ) f
WHERE seqnum = 1;
ORDER BY f.title, "agent_total_profit" DESC;